A wiring incorporated resin pipe is generally formed by being molded, for example by, injection molding, extrusion molding and so on, to obtain a target diameter and length. As a method of coating a conductive wire for electric wiring, for example, the conductive wire is inserted into a crosshead at an end of an extrusion molding machine, thereby performing extrusion molding while coating a periphery of the conductive wire with a coating resin.
When the wiring incorporated resin pipe is molded by extrusion molding by combining these related art techniques, it is easy to imagine that a resin pipe with a conductive wire arranged inside the pipe can be manufactured by inserting the conductive wire into the crosshead at the end.
However, in the wiring incorporated resin pipe manufactured by the method of the above combination, wiring inside the resin pipe is also cut at the same time when the resin pipe is cut into an arbitrary length, an end surface of the resin pipe and an end surface of wiring are disposed side by side on the same plane, therefore, creating problems such as extreme difficulty in performing electrical connections to the outside and to add and or connect terminals.
In view of the above problems, a method described in JP-A-H6-341587 (Patent Literature 1) was developed. FIG. 23 and FIG. 24 show a method of incorporating wiring into a pipe described in Patent Literature 1.
FIG. 23 shows an inner tube member 41 for a nominal diameter (inner diameter of a tube) 200 mm before groove processing, which is an almost cylindrical shape with an inner diameter D is approximately 218 mm and a wall thickness “t” is 5 mm. Pedestals 42a and 42b to which connector pins are attached are provided on outer surfaces of both ends, which are formed of a thermoplastic resin such as polyethylene.
Spiral-shaped grooves 43 shown in FIG. 24 are machined with respect to the inner tube member 41. Then, a heating wire is wound in the grooves 43 and connector pins are connected to be attached to the pedestals 42a and 42b. Separately, an outer tube member is integrally formed by injection molding to complete an electric fusion type plastic tube joint.